Cornea Eyes - one of the most important parts of the human eye

One of the most important parts of the human eye is the cornea, which protects it from damage and infections. However, she herself is very vulnerable, subject to various diseases.

The cornea of the eye protects the anterior part of it and is the outer dome-shaped surface of the eye; It does not contain the blood vessels needed to feed most tissues of the human body, it differs in optical homogeneity. In order to qualitatively refract light, the cornea should be transparent, the presence of even very small vessels will interfere with this process. The magnitude of refraction of the cornea of the eye is 43 diopters. Its diet is mainly obtained from tears and watery moisture in the anterior chamber.

The cornea of the eye is often compared with the glass of the clock inserted into the frame, since the curvature of the cornea itself is somewhat greater than the curvature of the sclera. The cornea of the eye consists of five layers each having its own important function: epithelium, Descemet's shell, Bowman's layer, endothelium, stroma.

The anterior layer - the epithelium - is formed from polyhedral flat cells. Next comes the Bowman layer - a homogeneous structureless front boundary plate. Actually, the very substance of the cornea is called the stroma, it consists of the finest connective tissue plates alternating with each other, containing many finest fibrils. The role of a gluing agent is the mucoid, which contains sulfogyaluronic acid, which ensures the transparency of the cornea. Stroma does not contain blood vessels and is very slowly restored. The descemet's membrane, or membrane, is a posterior, very dense, border plate, its fibrils composed of a special substance that is identical to collagen; It regenerates well. Endothelium (or posterior epithelium of the cornea) is a layer of flat hexagonal prismatic cells close together. This layer is responsible for the transparency of the cornea and is not completely restored.

The cornea includes 80% water, 18% definitive collagen, about 2% mucopolysaccharides, lipids, proteins, vitamins C, B, etc. In the elderly, the cornea contains much less vitamins and moisture, globulin fractions of the protein, And also deposited lipids and calcium salts. The consequence of such changes is a change in the transition of the cornea (limbus) to the sclera - the layers of the sclera begin to "move" on the cornea and there is a so-called senile arc, the sensitivity of the cornea decreases and its refractive power decreases. In addition, its permeability for eye drops, ointments and nutrients is greatly reduced.

The sensitivity of the cornea of the eye (innervation) with the trigeminal nerve. Especially a lot of nerve endings in the surface layers, least of all - in the endothelium. In newborns, the cornea of the eye is insensitive because of the unfinished development of the cranial nerves, and at the age of one year its sensitivity is almost the same as in adults.

Due to the fact that the cornea is the outer shell of the eye, it constantly contacts the external environment. Therefore, there are special mechanisms for protection from harmful external influences and injuries:

1. Reflex closure of the eye;
2. Flushing off the surface of the cornea of harmful agents with the help of tears;
3. Fast and complete recovery of the epithelium.

The main diseases of the cornea are: developmental anomalies, dystrophic and inflammatory processes (sclerites, keratitis) and tumors.

Among pathologies, inflammation of the cornea of the eye or keratitis occurs most frequently. Keratites are exogenous and endogenous. Very often after the transferred keratitis there is a clouding of the cornea of the eye of different degree of severity. By the intensity of turbidity and its magnitude, there are hazards in the form of belly, spots and clouds. Belmo is a persistent opacification of the cornea of the eye, which is caused by cicatrical change, occupying part of the cornea or the entire cornea. A spot is a persistent intense clouding of the cornea with distinct edges on the periphery or in the center. The cloud is a limited clouding of gray that is barely visible when viewed.